Molten urea dyeing process



United States Patent MOLTEN DYEING PROCESS Samuel Nelson Bradshaw, Coventry, England, assignor to Courtaulds Limited, London, England, .a British company No Drawing. Application June 12 6 1957 Serial N0. 668,043

Cl ms p o ty, app i a i eat B ita M 6 .9

8 Claims. (Cl. 8-35) may also contain one or more dyeing assistants, for

example common salt or Glaubers salt or other compounds which assist the material in taking up the dye and give a uniform penetration of the material by the dye. In the normal dyeing process therefore water is the usual medium i which he dye is nsf d tot textile mat r al The object of the present invention is to improve the dyeing of organic textile materials; a According to the present invention a process for dyeing organ textile mat r als p se impregnati the textile material with a solution of urea and with an aqueous solution or dispersion of at least one dyestufi which is soluble in molten urea and is substantive to the text l m te iahd y s the e t l a e al at a temp ture below the melting point of urea (132 C.), heating the dried material in the absence of steam at a temperature between the melting point of urea and 160 C. to melt the urea whereby it serves as a solvent for the dyestuff, from which resultant solution transfer of the dyestuft to the material takes place, washing the dyed material to remove the urea and again drying the material.

An essential feature of this invention is that molten urea is used instead of wateras the dyestutf transfer medium.

n, a preferred methodof carrying out the invention the text-ilematerials are impregnated with a single solution of urea in which the dyestufl is either dissolved or dispersed, the impregnated material is dried at a. temperature below the melting point of urea and then baked at a temperature above the melting point of the urea, this baking being essentially a dry heating in the absence of steam, The impregnation is preferably effected at room is preferably effected at about C. After the baking the dyed textile materials are washedto remove the urea and then dried.

The process .ofthe present invention is suitable for dyeingwith dyestuffs which are soluble inmolten urea for example direct cotton dyestuffs, dispersed acetate dyestuffs, soluble acetate dyestufis,'leuco esters of vat dyestuifs, aggregated acid dyestufis and metal complex dyestuffs. It is particularly suitable for dyeing cotton and regenerated cellulose with direct cotton dyestuifs. The material used must be substantive to the dyestulf being used since the use of urea as a transfer medium in accordance with this invention does not extend the range of dyestuifs available for dyeing any particular type of textile material. 7 7

The process of the present invention is suitable for dyeing those organic textiles which are not deleteriously affected by baking at a temperature of to C. for example textile materials of cotton, wool, regenerated cellulose, artificial protein fibres, cellulose esters, for ex ample secondary acetate and triacetate fibres, synthetic polyamides, synthetic polyesters, polyacrylonitrile and the like and materials made from mixtures of two or more of these fibres. it"is not suitable for dyeing glass and other mineral fibr'es. If the process is used for dyeing textiles from thermoplastic fibres having a comparatively low melting point for example certain vinyl resin fibres the baking should be carrier out at the lower temperature and for the shortest time permissible.

I have found that, apart from the one class of easily levelling acid dyes on nylon which requires strongly acid dyeing conditions, the process of this invention can be used with any dyestuff for which water is known to be a suitable transfer medium. Thus if it is known that a dyestufi can be satisfactorily applied to a particular textile material from an aqueous dyebath, other than a strongly acid dyebath as in the case of the easily levelling acid dyestuifs, it can beassumed that it can also be applied to the same material using urea as a transfer medium in accordance with this invention. The following test may however be used to determine whether any particular to a dry filter paper which has previously been impregnated with a 50 percent aqueous solution of urea and dried. The test paperis then placed for about 3 minutes in an oven which is, maintainedat a temperature slightly above 132 C. Coloured haloes are formed if the dyestnfi is soluble in. molten urea. Such a test does not define the degee of solubility but the actual degree of solubility is immaterial; if the conditions specifiedin the ,7

test are satisfied, 'i.e. a coloured halo is formed, the dye? stuff can beused in the process ofthis invention. When used in the specification and claims of this application, the term dye which is soluble in molten urea means a dye which complies with the test set out above.

As, in thefcase of dyeing from aqueous baths, two or more substantive dyestuffs may be applied simultaneously.

The following lists give examples of suitable dyes for dyeing various textile materials (references are to the Color Index, second edition):

Foe. corroN AND 'REGENERATED CELLULOSE Chlorantine Brown BRLL (Clayton Dyestufis Ltd.) (C1. a

Direct Brown 95) Solophenyl Blue Green BL -('Geigy-) 0.1. Direct Green 27) Durazol. R d (LOL) (C1. Direct Red 81) may be used. Examples are:

aeasgii Durazol-Red 6B (I.C.I.-) (C.I. Direct Red 79) Durazol Orange 26 (I.C.I.) (C.I. Direct Orange 34) Diphenyl Chlorine Yellow FF (Geigy) (C.I. Direct Yellow 28),

And related dyestufis.

, FOR CELLULOSE ACETATE J 1 All dispersed dyes may be used; Examples are;

Serisol Fast Scarlet GD (Yorkshire Dyeware Chemical Co.) (C.I. Disperse Red 19) Solubilised vat dyestuffs can also be used. Typical examples are: y j Soledon .Jade. Green XS (I.C.I.) (C.I.- solubilized vat green 1) Soledon Golden Yellow RKS (I.C.I) (C.I. solubilized vat orange 1) j i Y Sulphonated hydroxy-ethyl derivatives of certain dyes may also be used, for example the Solacet range of dyes by I.C.I.

FOR CELLULOSE TRIACETATE The dispersed dyes and solubilised vat dyes, and those specifically given above under cellulose acetate,-may also Sevron Blue 26 (Brown & Forth) (C.I. Basic Blue 22) Sevron Yellow L (Brown & Forth) (C.I."Basic Yellow Dispersol Fast Crimson B (C.I. Disperse Red 13) is i .an example of a suitable dispersed dye. If the acrylic fibre contains a dyeableadditive such as polyvinyl pyridine then thewhole range. of acid dyes may beused. 7

FOR NYLON V V Dispersed dyes may be used. Examples are:

:Serisol Fast Scarlet GD (YorkshireDyeware i Co.) (C.I. Disperse Red 19) a Serisol Brilliant Blue 36 (Yorkshire Dyeware & Chemical Co.) (C.I. Disperse Blue 3) .Dispersol'Fast Crimson a 1.0.1. (C.I. DisperseRed i3) Sulphonated hydroxy-ethyl derivatives of dispersed dyes 'Solacet Fast Crimson B (I.C.I) (C.I. Acid Red 159 'SolacetScarletB (I.C.I.) (C.I. Acid Red 53) i e Solacet Fast Blue 2B (I.C.I.) (C.I. Acid Blue 14) Metal complex dyes maybe used. Examples are;

Vialon Yellow G (Allied Colloids Ltd.) (2.1. Acid Yeljfulow11l8) Vialon Fast Brown R (Allied Colloids Lt d4) (C.I. Acid Brown 50) green 1) orange 1) 1 See Journal of Society of Dyers and Colourlsts. 'vol 71. page 45:).

viscose rayon staple fibres and 33 percent of regenerated .4 Aggregateddyestufis may alsobeused... Examples are:

Coomassie Red PGS (I.C.I.) (C.I. Acid red 85) Carbolan Yellow RS (I.C.I.) (C.I. Acid yellow 71) Coomassie Fast Yellow GS (I.C.I.) (C.I. acid yellow 85) Carbolan Crimson BS (I.C.I.) (C.I. acid red 138) FOR POLYESTERS (TERYLENE; DACRON) Dispersed dyestuffs, particularly rapidly diffusing dyestuffs, may be used. Examples are:

Dispersol Fast Yellow G (I.C.I.) (C.I. Disperse Yellow 3) E Dispersol Fast Orange G (I.C.I.) (C.I. Disperse Orange V 3) a i Duranol Red'GN (I.C.I.) (C.I. Dispers'e Red 9) Duranol Red "2B (I.C.I.) (C.I. Disperse Red 1 5) Duranol Violet 2R (I.C.I.) (C.I. Disperse Violet 1) take-up of urea and the. optimum length of time of baking for a particular dyestufi? and fora particular textile.

material. The upper limit of the temperature of baking (160 C.) is determined by the tendency for urea to decompose at elevated temperatures. Am/suitable. apparatus can be used to carry out the process, for example, thetextile material may be impregnated with ureai'and a dyestufi from. an aqueous solution on a padmangle and the impregnated material may be dried and baked in an oven. The apparatus normally used for carrying out a crease-resist treatment with a urea-formaldehyde resin on textile materials can be used without substantial alteration. i p

The process of this invention using urea as'transfer 3 medium, compared with the customary technique using aqueous dyebaths, has several advantages. For example dye transfer with urea is considerably quicker, the urea process can be carriedout in a'continuous manner and is more economical, and also the urea processoften gives levelness of dyeingfwhere aqueous baths would not,.for

' examplein the dyeing of so-called s tripey fibres where any ,difierences .in dyeing aflinity are levelled out by usingthe urea process. The urea dyeing process does not substantially affect the strengthof the fibres.

. 'T he invention is illustrated by the following examples.

7 Example 1 A sample of woven fabric containing 67 percent of (M grant ofDurazol GS (I.C.I.) (C.I.;D irect Yellow 28) 0.4 gram of Durazol Blue 2on5 (C.I.Direct Blue 76 Soledon G olden Yellow RKS (I.C.I.) (c.I. solubiliaedivat page-534), and -40 grams of urea (Journal of the Society ofDyers and Colourists, 1952,

and then baked foriwm minutes at l40" C. The dyed sample was washedfor ten minutes in cold water and dried at C.

A. comparable dyeingcarried 'out inflaccordance with normalpracticewas carried out on asecond sample of h's r j imat ia i I qd eh h. was an a q q 1. 1-

'0;4 perc'entof. :Dufrazol Blue 2G-NS (Journal of the Society of 'Dyers"anc1..,Colourists, 1952; page'534) 10 percent of Glaubers salt a All the percentages were based on the Weight of the textile material, and the dyebath had a liquor to fabric ratio of 40:1. The dyeing was carried out for one hour at 90 C. The sample was then washed in cold water and dried at 80 C.

On comparing the two methods it was found that the fabric dyed by the process of the present invention was quite even, whereas the fabric dyed from an aqueous dyebath showed a degree of differential dyeing and was consequently unevenly coloured.

On subjecting the dyed fabrics to the washing test as described in the Second Report of the Fastness Tests Committee of the Society of Dyers and Colourists (Journal of the Society of Dyers and Colourists 1948, volume 64, pages 136-7, Test No. 1) it was found that the fabric dyed by the process of the present invention was of comparable fastness to the fabric dyed from an aqueous bath.

Example 2 A fabric woven from 100 percent viscose rayon staple yarn was padded at 110 percent expression through a solution at room temperature prepared as follows:

1 gram of Durazol Yellow 3R5 (1.0.1.), and 40 grams of urea Example 3 A fabric woven from 100 percent viscose rayon staple yarn was padded at 110 percent expression through a solution at room temperature prepared as follows:

1 gram of Durazol Rubine BS (I.C.I.) (C.I. Direct Red 82), and 40 grams of urea were made up to 100 cubic centimetres with water. After drying in a circulating air oven at 80 C., the fabric was divided into two parts, which were treated as described in Example 2. Similar results were obtained,

the unbaked sample showing severe loss of colour; the baked sample showed substantially better retention of the dyestuif.

Example 4 A fabric 20 yards long and 36 inches wide woven from yarns of regenerated cellulose. staple fibre was padded at 100 percent expression through an aqueous solution at room temperature containing 50 percent urea 1.25 percent Chlorantine Brown BRLL 200 percent (Clayton Aniline Co.) (C.I. Direct Brown 95) 1 percent Calsolene Oil The fabric was dried for three minutes at 80 C. by a single passage through a circulating air drying chamber. The fabric was then baked by passing it again through the same chamber at 140 C. for three minutes. The cooled, baked fabric was washed for 15 minutes in water at 30 C. and finally dried at 80 C.

A smaller length was dyed' to a similar winch using a dyebath containing 1.25 percent Chlorantine Brown BRLL 200 percent (on weight of fabric) 7 20 percent Glaubers'salt (on. weight of fabric) shade on a .6 at a bath ratio of 40: 1. The time or dyeing was.

"2% hours and thetemperature of the dyebath C.

On subjecting both fabrics to the washing test as 'described in Example 1, it was found that the two fabrics were of comparable washing fastness.

Tests also showed that the two fabrics were of comparable light fastness.

Example 5 I A circular knitted fabric containing 67 percent of wool and 33 percent of regenerated protein staple fibres was padded at percent expression through a solution at room temperature prepared as follows:

were made up to 100 cubic centimetres with water. The material was then dried in a circulating air oven at 80 C. and baked for 10 minutes at C. Another sample of the same fabric was padded similarlyrthrough a solutionmade up as above but with the'urea omitted, and ried and baked as described. v H

On subjecting to the washing test described in Example 1, it was found that'the sample padded without urea showed severe loss of colour, whereas the sample padded with urea showed satisfactory retention and exhibited no bleeding on to undyed wool and cotton fabrics present during the test.

Example 6 A cutting of warp knitted nylon fabric was padded through a solution at room temperature prepared as follows:

1 gram of Vialon Yellow G (CI. Acid Yellow 118) (Badische Anilin & Soda Fabrik) 2 grams of Calsolene Oil, and

40 grams of urea were made up to 100 cubic centimetres with water. The

fabric was dried in a circulating airoven at 80 C.and baked for 10 minutes at 150 C. A further portion of fabric was padded through a solution made up as above, but with the urea omitted, and similarly dried and baked. On washing'in cold water it was found that the fabric padded without the inclusion of ureashowed marked loss of dyestutf and gave only a pale shade. The presence 'of urea resulted in a shadeof substantially greater tinctorial value. ,7

Example 7 A padding solution was prepared as follows:

50 parts urea, a

3 parts Duranol Violet 2R 300 (I.C.I.)' (C.I. Acid ViO- let 1),

1 part sodium carboxymethyl cellulose,

1 part Dispersol VL (a non-ionic dispersing. agent sold by Imperial Chemical Industries Ltd.)

made up to 100 part swith water. I

A fabric woven from yarns of polyester fibres sold under the registered trademark Terylene. was padded through this solution at 35 percent expressiomdried for three minutes at 80 C., baked for three minutes at C., washed in water at room. temperature: and dried at I 80 .C. V 4

.ZLAzsimilar piece of fabric waspot dyed for 1 hours at the boil using an aqueous dyebath containing:

"1' percent Duranol Violet 2R 300 (I.C.I.), and percent Dispersol VL (I.C.I.),

at a bath ratio of 40:1. I I I On subjecting both fabrics to the washing test described in Example 1 it was found that both fabrics were of good wash fastness (4 to 5), the urea dyed fabric showing slightly greater fastness. a

I Examples to Further samples of fTerylene fabrics as used in Example 7 were dyed in the same way as described in Example 7 except that the padding solution contained, instead of three parts of Duranol Violet 2R 300,

Example 8: 3 parts of Dispersol F Yellow G 300 (I.C.I.)

-(C.I.v Disperse Yellow 3) Example9: 3 parts of Dispersol F Orange G 300 (I.C.I.)

(C.I. Disperse Orange 3) Example 10: 3 parts of Duranol Blue ZGN 300 (I.C.I.)

( C.I, Disperse Blue 24).

Acutting of plain woven continuous filament cellulose 1 acetate fabric was padded at 70 percent expression th ou h an aqueous solution-at room temperature con- 1.4 parts Dispersol Yellow G 300 (I.C.I.) (C.I. Disperse Yellow 3) "45 parts urea, and

2 parts Calsolene Oil HS,

Example 12 A cutting of the fabric similar to that used in Example 11 was padded and baked as described in that example using Duranol Blue Green B (I.C.I.) (C.I. Disperse Blue 7) in place of Dispersol Yellow G. A-further cutting was dyed from an aqueous bath again as described in Example 11 but using Duranol Blue Green B in place of Dispersol Yellow G. On subjecting thedyed fabrics to the washing test as described in Example 1, both fabrics showed wash fastness of a similar order.

Example 13 A cutting bleached plain woven 100 percent cotton fabric was padded through an aqueous solution at room temperature containing made up to 100parts'withwater. I 2 1 The cutting was dried at C., baked for four minutes 8 .at I45 C., and rinsed in cold water. A second cutting dyed from an aqueous bath containing l percent Chlorantine Brown BRLL (on weight of fabric),

10' percent Glaubers salt (on weight of fabric).

The bath ratio was 40:1' and the time and temperature ofdyeing hour at C. On subjecting the dyed fabrics to the washing test as described in Example 1, the wash fastness of both samples was found to be similar.

Example 14 V The dyeings and tests described in Example 13 were repeated using instead of Chlorantine Brown BRLL, Chlorantine Green SGLL (Cl. Direct Green 28). Again the dyed fabr cs were of comparable wash fastness.

A cutting of fabric woven from percent viscose rayon staple was padded, at room temperature, through a solution containing 1 gram Solochrome Azurine B (C.I. Mordant Blue 1), (I.C.I.), I I

2 cubic centimetre basic chromiumacetate (32 Tw), and

50 grams urea,

made up to 100 cubic centimetres with water.

The cutting was dried at 80? C., baked for four minutes atl C., and finally washed in cold water. As dried, the fabric was a beige colour but turned blue during the baking stage. On submitting the fabric to the washing test, as described in Example 1, it was found that a satisfactory wash fastness had been obtained. Filamer ts taken from the fabric wereexamined in crosssection under the microscope, and the dyestuif was seen to be deposited throughout the filaments.

Example 16 A cutting of knitted fabric made from cellulose acetate yarn was padded through a solution containing '1 gram Soledon Jade Green zos, (I.C.I.) 0.1. solubilized vot-green 2), and 50 grams urea,

made up to 100 cubic centimeters with water.

It was then dried at 80 C., baked for four minutes at 145 C., and washed in cold water. During the baking stage the colour of the fabric changed from violet-brown (the colour of the leuco ester of the dyestutf) to green, thecolour of the parent dyestuff. No significant change of shade was evident after treatment for /2 hour at 80 C. in 0.2 percent soap solution. f It has been found that certain leuco-esters of vat dyestuffs" do'not show this reversion to the shade of the parent dyestuff on baking. In these cases orthodox methods of regeneration may be carried out after baking, for example atmospheric oxidation, or oxidation by means of oxidising agents.

Example 17 1 gram of Serisol Brilliant Blue B6 (C1. Disperse Blue '3), and 5O gramsof urea,

' made up to 100 cubic centimetres with water.

The fabric was dried at 80 C., baked for four minutes .a t 145 C., washed in water and dried. The fabric was-dyed blue. I II I I Example 18 A knitted fabric made fromyarn consisting of a polygner of 95 pe rcjent ofacrylonitrile and 6 percent of methyl acrylate was padded through a solution containing .1. gramof. Sevron Blue 26. (Cl. basic blue 22), and

made up' 150.100 cubic centimetres with water.

The fabric was dried at 80 C., baked for four minutes at 145 C., washed in water and dried. The fabric was dyed blue.

In the baking step in the process of the present invention the urea melts and acts as a dye transfer medium. The process of the present invention provides a simple and convenient alternative to the established practice of dyeing from aqueous dyebaths. The process is simple, quick, easy to control and eliminates many of the difiiculties encountered in dyeing with aqueous dyebaths.

The process is particularly suitable for dyeing blends of two or more different fibres especially where one of the fibres shows a preferential absorption for the dyestuff from an aqueous dyebath, for example blends of viscose rayon fibres and regenerated protein fibres can be dyed in an even shade with a direct cotton dyestufi by the process of the present invention whereas the blends would be ditferentially dyed from an aqueous dyebath.

The process is also particularly suitable for dyeing textile materials of synthetic polyesters, for example of polyethylene terephthalate.

What I claim is:

1. A process for dyeing organic textile materials which endure baking at 130 C.160 C. which comprises impregna'ting the textile material with a solution of urea and with an aqueous solution or dispersion of at least one dyestufi which is soluble in molten urea and is substantive to the textile material, drying the textile material at a temperature below the melting point of the urea, heating the dried material in the absence of steam at a temperature sufficient to melt the urea and not higher than 10 160 C. whereby the urea is melted and serves as a sol vent for the dyestuff, from which resultant solution transfer of the dyestuft to the material takes'place, washingthe dyed material to remove the urea and again drying the material. r

2. A process as claimed in claim 1 wherein the solution of urea used is an aqueous solution.

3. A process as claimed in claim 1 wherein the textile material is impregnated with a single solution of urea in which the dyestufi is dissolved or dispersed.

4. A process as claimedin claim 1 wherein the textile materials dyedcomprise regenerated cellulose.

5. A process as claimed in claim 1 wherein the textile materials dyed comprise wool.

6. A process as claimed in claim 1 wherein the textile materials dyed comprise nylon.

7. A process as claimed in claim 1 wherein the textile materials dyed comprise cellulose acetate.

8. A process as claimed in claim 1 wherein the textile materials dyed comprise acrylic fibre.

References Cited in the file of this patent V UNITED STATES PATENTS 1,963,975 Ellis June 26, 1934 2,080,254 Dreyfus May 11, 1937' FOREIGN PATENTS 996,335 France Dec. 18, 1951 505,597 Canada Sept. 7, 1954 230,891 Switzerland May 16, 1944 

1. A PROCESS FOR DYEING ORGANIC TEXTILE MATERIALS WHICH ENDURE BAKING AT 130*C.-160*C. WHICH COMPRISES IMPREGNATING THE TEXTILE MATERIAL WITH A SOLUTION OF UREA AND WITH AN AQUEOUS SOLUTION OR DISPERSION OF AT LEAST ONE DYESTUFF WHICH IS SOLUBLE IN MOLTEN UREA AND IS SUBSTANTIVE TO THE TEXTILE MATERIAL, DRYING THE TEXTILE MATERIAL AT A TERMPERATURE BELOW THE MELTING POINT OF THE UREA, HEATING THE DRIED MATERIAL IN THE ABSENCE OF STEAM AT A TEMPERATURE SUFFICIENT TO MELT THE UREA AND NOT HIGHER THAN 60*C. WHEREBY THE UREA IS MELTED AND SERVES AS A SOLVENT FOR THE DYESTUFF, FROM WHICH RESULTANT SOLUTION TRANSFER OF THE DYESTUFF TO THE MATERIAL TAKES PLACE, WASHING THE DYED MATERIAL TO REMOVE THE UREA AND AGAIN DRYING THE MATERIAL. 